核动力工程

Study on Effect of Transverse Power Distribution on Temperature Field of Plate Type Fuel

Lu Qing, Yu Hongxing

2015, 36(S2): 1-3. doi: 10.13832/j.jnpe.2015.S2.0001

Abstract(29) PDF(0)

Abstract:
The temperature field in the plate type fuel and coolant is investigated. One of the typical IAEA-10 MW-MTR fuel and coolant channel is modeled and simulated with CFX-Fluent. Three different power distributions are considered, which are uniform distribution, higher central power distribution and lower central power distribution in the transverse direction of the fuel plate. Results indicated that there is a cooler coolant center near the corner of the channel, because of no heat generation in the structure plate and the transverse heat conduction. Suggestion is proposed, which is that the power distribution and heat conduction in the transverse direction in the fuel plat should be considered in the nuclear physics design, thermal-hydraulic design and safety analysis.

Development and Verification of System Safety Analysis Code TSACO

Wang Jie, Pan Junjie, Feng Jintao, Su Guanghui

2015, 36(S2): 4-8. doi: 10.13832/j.jnpe.2015.S2.0004

Abstract(31) PDF(0)

Abstract:
The HE-FUS3 facility was organized to assess the capability of system code in simulating the thermal-hydraulic and dynamic behavior for High Temperature Gas Reactor. The TSACO（Thermal hydraulic and Safety Analysis code） modeled the HE-FUS3 helium facility at the initial steady state and loss of flow accident（LOFA）. The calculated temperature distributions in the loop at the initial steady state are compared with the measured temperatures. The flowrate and test section outlet temperature for LOFA are compared. The calculated results at both steady state and LOFA accident are in good consistent with the experimental results. Good agreements of the experimental and computational results proved the rationality and accuracy of the TSACO modeling.

Design Method Investigation of Operation Mode in Advanced PWR

ZHou Jinman, Liu Tongxian, JIang Zhumin, Wang Jinyu, Liu Qiwei, Liu Xiaoli, Gong Zhaohu

2015, 36(S2): 9-13. doi: 10.13832/j.jnpe.2015.S2.0009

Abstract(32) PDF(0)

Abstract:
This paper investigates the overall design of operation modes in PWRs, and brings forward a design method for operation mode in the advanced PWR. The design method tidies up all aspects of operation modes, arranges the sequence of all aspects, and focuses on the keystones of all design aspects. This paper investigates three operation modes, including Base Load, Load Follow with Boron Change and Load Follow without Boron Change, and brings forward their characteristics and design methods. Finally, the design results of the Load Follow with Boron Change and the Load Follow without Boron Change, which have been accomplished with the guidance of this design method, are presented. The application of these design results in CPR1000 and the 3^rd generation PWR proved that this design method of operation modes in PWR is correct and feasible.

Neutron Penalty and Advantage Analysis of Candidate Accident-Tolerant Cladding Materials in PWRs

Ni Dongyang, Li Mancang, Wu Wenbin, Sun Wei

2015, 36(S2): 14-16. doi: 10.13832/j.jnpe.2015.S2.0014

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Abstract:
This paper analyzes the neutron penalty and advantage of the candidate accident–tolerant cladding materials 304 SS, 310 SS, FeCrAl, APMT and SiC. The results show that the sequence from high to low is: SiC＞Zr＞FeCrAl＞APMT＞304SS＞310SS. After using a thinner cladding of 0.4 mm and keeping a constant outer diameter, Fe-based alloys require an increase of no more than 0.5%, for achieving the same fuel cycle length [about 60000 MW·d/t（U）] as the zircaloy’s, while Si C requires less enriched uranium about 0.12% by using a standard cladding thickness.

Solving 3-D Neutron Diffusion Equation with JFNK Algorithm

Wu Wenbin, Li Qing, Sun Wei, Wei Yanqin

2015, 36(S2): 17-19. doi: 10.13832/j.jnpe.2015.S2.0017

Abstract(26) PDF(0)

Abstract:
In this paper, 3-D neutron diffusion equation was discretized into the generalized eigenvalue problem of large sparse matrix with finite difference method. Then, k_eff and power distributation were obtained by nonlinear algorithm JFNK（Jacobian-Free Newton-Krylov）. Numerical results demonstrated that JFNK algorithm could get high accuracy for 3-D neutron diffusion equation.

Model Establishment for Small Modular Reactor Using MAAP Code and Study on Fission Product Release Characteristics under Severe Accident

Wang Junlong, Wei Shuping, Liu Jiajia, Tan Yi, Lyu Huanwen

2015, 36(S2): 20-23. doi: 10.13832/j.jnpe.2015.S2.0020

Abstract(40) PDF(3)

Abstract:
Using MAAP code, a plant model was established for the small modular reactor（ACP100）. The behaviors of the model were tested on the steady state condition. It shows good consistency and the errors were 1% between the calculated values and designation values. Based on the model, a simulation was conducted in the case of severe accident, and the development process and source terms released into the environment are analyzed. It can be seen that the cumulative release fraction of nobles is liner with the time and increased with time. Other groups release fraction reach a maximum after a period of time and keep constants after that. The analysis results are provided as the essential input data for quantifying the release of ACP100 and the offsite dose analysis.

Xenon Stability Analysis for 1000 MWe PWR Core

Wang Shiqian, Wang Jinyu, Liu Qiwei, Chen Zhang, Li Qing, Li Xiangyang

2015, 36(S2): 24-26. doi: 10.13832/j.jnpe.2015.S2.0024

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Abstract:
Since PWR is inherently stable toward total power oscillations and it is protected by the control and protection system, our analysis focuses on xenon-induced power oscillations, including axial oscillation and radial oscillation. This paper uses 1D and 3D programs to build Xenon transients, and analyzes axial oscillation and radial oscillation, to validate that the core is inherently stable or can be controlled toward xenon-induced oscillations. The results show that the core is inherently stable toward radial xenon-induced oscillations. Stability of the first cycle is worse than that of the equilibrium cycle. But through the operation by the control system, the core can stay safe, and the fuel design limit can be respected.

Study on Physical Performance of Uranium Zirconium Hydride Power Reactor with Tight Lattice Core

Wei Yanqin, Wang Lianjie, Li Qing, Chen Bingde, Sun Wei, Wu Wenbin

2015, 36(S2): 27-29. doi: 10.13832/j.jnpe.2015.S2.0027

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Abstract:
The core loading pattern and physics performance of the uranium zirconium hydride power reactor with close packed lattice fuel assemblies are studied with the renewed in-core fuel management code package. The study shows that although the UZr H_1.6 tight lattice reactor has less uranium than UO₂ core which has the same disposal, it retains the higher inherent safety and the flatted power distribution.

Research on In-Pile Irradiation Structures of Second-Generation Plus Nuclear Power Plants

Fang Caishun, Zhang Hongliang, Liu Xiao

2015, 36(S2): 30-32. doi: 10.13832/j.jnpe.2015.S2.0030

Abstract(35) PDF(0)

Abstract:
Material radiation ageing should be considered in the aging analysis of the reactor internals of nuclear power plants. At present, there is still no material irradiation data of reactor internals at home. Operating history shall be considered for different reactor types or specific rectors. For the purpose of understanding the effect of material radiation ageing on the reactor internal accurately, a new scheme of in-pile irradiation structures is put forward.

Research on Improvement for Calculation Formula of Ring Spring Design

Du Hua, Wang Liubing, Li Ning, Peng Hang, Fang Caishun

2015, 36(S2): 33-36. doi: 10.13832/j.jnpe.2015.S2.0033

Abstract(27) PDF(0)

Abstract:
Finite element analysis method is used to solve the problem that calculation formula in spring manual is not applicable for a special ring spring in high temperature environment. This special ring spring has a single layer outer ring structure, and material of the inner ring is different from the material of the outer ring. Based on the results of finite element analysis, an improved calculation formula for ring spring design has been established.

Study on Separating Speed of Cam Anti-Reverse Device In Shield Pump

Liu Songya, Zhao Xuecen, Liu Lizhi, Deng Liping

2015, 36(S2): 37-40. doi: 10.13832/j.jnpe.2015.S2.0037

Abstract(29) PDF(0)

Abstract:
Cam anti-reverse device is put forward in this paper, which has the similar work principle with the friction anti-reverse device used in nuclear power stations, but has more simple structure, less rotating parts, and smaller size. Against the key problem of the separating speed when the rotates, the simulation model is established based on the theory of fluid lubrication and solved with Matlab language. In the end, combined with a shield pump structure size, the cam anti-reverse device is designed, and the relationship of the forward speed, the degree of deviation and the pressure torque is calculated and analyzed. The results show that the cam anti-reverse device can separate when the rotor speed rises to a certain speed.

Study on Isolation and Depressurization Scheme for Pressurizer of Research Reactor

Zeng Chang, Lai Jianyong, Yu Xiaoquan, Su Rongfu, Tang Hui

2015, 36(S2): 41-45. doi: 10.13832/j.jnpe.2015.S2.0041

Abstract(28) PDF(0)

Abstract:
The numerical simulation models of local break and the entire system under loss of coolant accident（LOCA） for a certain gas pressurized research reactor are established. Based on the simulation of main pipe break, the relations among system flowrate, system pressure and break flowrate are studied, and the resistance characteristics of the break is obtained. Coupled the characteristic data with the system simulation model, the two schemes, isolation and depressurization, to prevent the gas into the reactor under LOCA accident are studied. The results show that, the break flowrate mainly depends on the system pressure, and the depressurization scheme is better than the isolation scheme.

Flow Analysis and Structure Optimization of Electric Heating Tank of Steam Generator Secondary Side Pre-Service Hydrostatic Test System

He Gening, He Jingsong, Li Donghui, Wu Ge, Huo Meng

2015, 36(S2): 46-49. doi: 10.13832/j.jnpe.2015.S2.0046

Abstract(32) PDF(0)

Abstract:
This paper conducts the fluid solid coupled three-dimensional numerical simulation on the electric heating tank,using the computational fluid dynamics（CFD） method. A new supporting plate structure is proposed by optimizing the design. The new structure can provide reliable support for the electric heater, and the highest surface temperature of the electric heater decreased significantly（reduce about 100℃）. The new structure can effectively prevent the liquid vaporization caused by local high temperature of the electric heater surface.

Verification for Periodic Test Frequency Extension in Nuclear Power Plants

Yu Xiaoquan, Zhang Xiaoyu, Yu Deyong, Ceng Chang

2015, 36(S2): 50-54. doi: 10.13832/j.jnpe.2015.S2.0050

Abstract(24) PDF(0)

Abstract:
Periodic test frequency shall be adjusted following the refueling cycle extension in nuclear power plants. This paper introduces the screening principle and verification methods for verification of periodic test frequency extension, and then takes containment spray system as an example, the feasibility of periodic test frequency extension is verified by the reliability analysis method. The quantitative result demonstrates that the reduction of system availability is acceptable to periodic test frequency extension.

Design and Verification Test of Wedge Graphite Seal Structure Used for Manway on Pressurizer

Li Yi, Chen Cong, Fu Xiaolong, Pei Liting, Peng Hang, Song Xiaoming, Xiao Kunjian, Li Xinggen

2015, 36(S2): 55-59. doi: 10.13832/j.jnpe.2015.S2.0055

Abstract(33) PDF(0)

Abstract:
This paper analyzed the structure option and studied the function parameter of the seal material. Numerical analysis was used to analyze the seal structure. Based on all above, the one-to-one scale hot state verification test was carried out. The test results showed that there was no leakage after the wedge graphite seal structure experienced the 100 cold-hot cycling test. And also the results showed the seal structure was easy to install and dismounte. The engineering feasibility of the wedge graphite seal structure was verified.

Simulation Calculation and Analysis of Temperature Measurement Bypass Line Steady State

Ren Yun

2015, 36(S2): 60-63. doi: 10.13832/j.jnpe.2015.S2.0060

Abstract(32) PDF(0)

Abstract:
The purpose of the design and layout of the reactor coolant temperature measurement bypass lines and the selection of throttle orifice are to ensure that the transit time of the reactor coolant meets the requirement of the safety criteria（equal or less than 1s）. The Flowmaster simulation model of the temperature measurement bypass lines have been analyzed, and compared to the commissioning data in the nuclear power plant. The analysis results prove that the design and layout of the temperature measurement bypass lines and the selection of throttle orifice are reasonable and correct, and the transit time of the reactor coolant can meet the requirement of the safety criteria.

Study on Calculation Method for Droplet Drag Coeffient Based on Dynamic Simulation and P Control

Zhang Di, Luo Qi, Huang Wei, Wang Kan

2015, 36(S2): 64-68. doi: 10.13832/j.jnpe.2015.S2.0064

Abstract(39) PDF(0)

Abstract:
Droplet drag coefficient is the key factor which affects the droplet behavior. And there is no mature and general drag correlation for droplets. The present work proposed a new approach to calculate the droplet drag coefficient: the single droplet motion in the uniform flow is simulated dynamically. By adding the body force source item to the momentum equation, the position of the droplet centroid is controlled leading to its approximative simple harmonic motion. The droplet drag coefficient is estimated by analyzing its position change. The present approach was realized by using VOF method to simulate the droplet-gas two-phase flow and validated by several example cases. Results showed that compared with the efficient PID control method, the present approach is more convenient to select the control parameter and even more efficient in the calculation.

Analysis of Anti-Windup Technique in NPP Control Systems

Wang Shu, Sun Jian, Li Wei, Chen Ke, Huang Qi

2015, 36(S2): 69-72. doi: 10.13832/j.jnpe.2015.S2.0069

Abstract(26) PDF(0)

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Concerning the problem of integral saturation in PID control which is commonly used in the control system, three algorithms of the anti-windup method are raised and applied to pressurizer pressure and steam dump to the atmosphere control systems. The simulation result shows that with making appropriate application of the anti-windup algorithm to different control systems, the requirement of system function can be met and the adverse effect caused by saturation can be avoided effectively.

Error Compensation Method of Advanced Digital Reactivity Computer Measuring with Range Spanning

Bao Chao, Zhu Hongliang, Ceng Shaoli

2015, 36(S2): 73-77. doi: 10.13832/j.jnpe.2015.S2.0073

Abstract(34) PDF(0)

Abstract:
Dynamic control rod reactivity measurement（DCRM） technique has been developed, and it can reduce the difficulties and shorten the time for the zero power physics test at PWRs. Advanced Digital Reactivity Computer（ADRC） is used in the process of DCRM. Different from the traditional using, the reactivity meter will conduct the multi-range measurement to satisfy the requirement for multiple ranges in the quick decreasing of the current. Error occurred in the range change has effects on the result of reactivity measurement. This paper analyzes the characteristics of the detector current curve in DCRM, and presents the error compensation method with curve-fitting. Test results in nuclear plants show that the method can decrease the error in the range change from 48% to 2%.

Heat Simulation Analysis on Mini Low Frequency Power Cabinet Based on Flo Therm

Cai Chen, Wu Ke, Lyu Xinzhi

2015, 36(S2): 78-81. doi: 10.13832/j.jnpe.2015.S2.0078

Abstract(34) PDF(0)

Abstract:
One miniature low frequency power cabinet was overheated, and the thermal can not be transmitted effectively from the heat sink in one new project. Considering this situation, this paper makes a complete thermal simulation analysis on the heating parts such as the IGBT modules, electrical source and drive power modules. The layout of the electrical components is optimized, and the heat sink module is improved, to maintain the cabinet element under the connect point temperature. The experiments on the prototype conformed that the heat simulation results are correct and the device optimization is achieved.

Virtual Design and Analysis of Bottom Nozzle in Fuel Assembly Based on Inventor

Gu Mingfei, Li Yuanming, Ru Jun, Zhu Fawen, Zhang Jibin, Li Quan

2015, 36(S2): 82-83. doi: 10.13832/j.jnpe.2015.S2.0082

Abstract(51) PDF(1)

Abstract:
The bottom nozzle, which main function is to support and fix the fuel assembly, is an important component of the nuclear fuel assembly. In this paper, we use the Inventor code to perform the three-dimensional modeling, virtual assemblage and finite element analysis of bottom nozzle.

Study on Thermal Performance of Accident Tolerant Fuel with UO₂ Mixed Pellet and Zircaloy Cladding Coating

Chen Ping, Liu Zhenhai, Li Wenjie, Xing Shuo

2015, 36(S2): 84-86. doi: 10.13832/j.jnpe.2015.S2.0084

Abstract(30) PDF(0)

Abstract:
The accident tolerant fuel consisted of UO₂ pellet mixed with propriety additive and zircaloy cladding smeared with special coating can reduce the fuel temperature and slow the zircaloy water reaction rate efficiently. In this paper, one of accident tolerant fuel design which is UO₂ pellet mixed with various weight percent SiC and M5 zircaloy cladding smeared with various thickness Si C coating is studied, the mixed UO₂ pellet–zircaloy cladding–SiC coating thermal relationship is built up and the thermal properties of mixed UO₂ pellet and Si C coating is collected. The long cycle fuel management for Qinshan II nuclear power plant unit 1 and unit 2 is selected as the background, the effect on fuel rod thermal performance and fission gas release of various weight percent SiC additive in UO₂ pellet and various thickness SiC coating on M5 zircaloy is analyzed comparatively, and the fuel rod performance under steady state and transient state is calculated in the end.

Numerical Simulation of Non-Linear Characteristics of Fuel Assembly Leaf Spring Hold-down System

Pu Cengping, Zhang Jibin, Qi Min, Ru Jun, Zhang Lin, Pang Hua

2015, 36(S2): 87-89. doi: 10.13832/j.jnpe.2015.S2.0087

Abstract(29) PDF(0)

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Hold-down system is one important part of the fuel assembly, which performance has important effects on the integrity and security of the fuel assembly. In this paper, the numerical simulation method for non-linear characteristics of the leaf spring hold-down system is studied. Then the method is verified by the calculated data comparing to the measured data.

Numerical Simulation of Control Rod Drop Sensibility under Different Flow Rates

MA Chao, Chen Ping, Xiao Zhong, Ru Jun, Pu Cengping, Li Yun

2015, 36(S2): 90-92. doi: 10.13832/j.jnpe.2015.S2.0090

Abstract(34) PDF(0)

Abstract:
The CRAC program was adopted to simulate the control rod drop process in the Chinese advanced fuel assembly under different flow rates. The comparison of the calculation results with the test results showed good agreement. The total rod drop time decreases with the decreasing of the flow rate; the calculation values for the largest and smallest drop time are very close to the test values; and the nominal calculation curve is close to the experiment curve.

Study on Corrosion Model for Zr-1Sn-1Nb-0.3Fe Zirconium Alloy

Zhang Kun, Guo Xingkun, Liu Zhenhai, Xing Shuo, Chen Ping

2015, 36(S2): 93-96. doi: 10.13832/j.jnpe.2015.S2.0093

Abstract(36) PDF(0)

Abstract:
Cladding material is the focus in the fuel assembly design, and the main characteristics that limit the cladding material is its corrosion performance. The corrosion mechanisms in zirconium alloys is complicated, and the neutron irradiation condition causes uncertain effects on the corrosion of zirconium alloys, and thus, it is difficult to estimate the zirconium alloy corrosion behavior and build the corrosion model just based on the out-pile corrosion test. In this paper, the corrosion model is built for the first time by analyzing the in-pile corrosion test results for Zr-1Sn-1Nb-0.3Fe.

Research on Stress Threshold of Stress Corrosion Cracking of Inconel 718 Alloy Hold-down Spring

Chen Liang, Pang Hua, Song Xiaoming, Liu Lili

2015, 36(S2): 97-101. doi: 10.13832/j.jnpe.2015.S2.0097

Abstract(28) PDF(0)

Abstract:
The proper heat treatment should be adopted to avoid those that have harmful delta phase along the grain boundary of Inconel 718 alloy, so it will not sensitive to the stress corrosion cracking in primary water condition. And more, stress threshold should be kept below 75%~80% of yield strength to avoid the stress corrosion cracking at stress concentrators, such as fillets. The design threshold stress value of hold-down spring, 931MPa（135ksi） is appropriate, but not conservative.

Theoretical Research on Effect of Heaving Condition on Flow Instability in Parallel Channels Based on Galerkin Nodal Method

Shen Yaou, Chen Wei, Ding Shuhua, QIan Libo

2015, 36(S2): 102-107. doi: 10.13832/j.jnpe.2015.S2.0102

Abstract(27) PDF(0)

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The lumped model of flow instability in parallel-rectangular channels under heaving condition based on Galerkin nodal method is built, in which the model of flow instability under static condition and the additional pressure drop generated by heaving condition is included and the effect of heaving condition on flow instability is analyzed theoretically in the present work. The results show that the amplitude of heaving condition has little effect on the flow instability; when the frequency of heaving condition is much larger or smaller than the system inherent frequency, the frequency has little effect on the threshold power, while when two of them are more or less the same, the threshold power will decrease. And when the system suffers asymmetric condition, the effect of heaving condition will increase significantly.

Validation of Analytical Capabilities of RELAP5 on Two-phase Nature Circulation by ESPRIT Tests

Li Feng, Yu Na, XIan Lin, Zhang Shu

2015, 36(S2): 108-111. doi: 10.13832/j.jnpe.2015.S2.0108

Abstract(32) PDF(0)

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Secondary passive system（PRS） is designed to remove the residual heat during 72 hours after the reactor trips in a 3rd generation reactor called Hualong I. To verify the ability of PRS system, the test facility ESPRIT is built and the height ratio is 1:1. Tests are consisted by three steady-states and two transients. One model of RELAP5 is developed and used to simulate the steady and transient tests. The results of RELAP5 is consistent with facility results, but underestimates the direct-contact condensation power.

Research on Improvement of DRM Methodology Based on Nonparametric Statistical Method

Chen Wei

2015, 36(S2): 112-115. doi: 10.13832/j.jnpe.2015.S2.0112

Abstract(25) PDF(0)

Abstract:
The DRM methodology uses the response surface method for uncertainty analysis, and introduces a penalization mode that covers the overall calculation uncertainty, which enables estimation of PCT with a confidence level greater than 95%. In this paper, taking the PCT as the target parameter, the nonparametric statistical method was used instead of the response surface method to perform uncertainty analysis in LB-LOCA accident. It was found that, the PCT of 95%/95% level based on nonparametric statistical method was enveloped by that based on DRM methodology.

Failure Criterion of Cladding Oxide Layer in Dissolution Mechanism

Liu Lili, Yu Hongxing, Chen Liang, Deng Jian, Zhang Ming

2015, 36(S2): 116-121. doi: 10.13832/j.jnpe.2015.S2.0116

Abstract(28) PDF(0)

Abstract:
A new failure criterion of cladding oxide layer dissolved by molten zircaloy is given based on the kinetics of molten zircaloy dissolve UO₂ and ZrO₂ simultaneously and its load conditions. The criterion was successfully validated against FPT-0 test. For a given structure of the fuel rod in nuclear reactors, the failure criterion can be simplified by temperature, which is a function of oxide scale and heat-up rate of the cladding. The relocation of melt in the flow path will be influenced by the new criterion predictions concerning mass and composition of relocated U-Zr-O mixture.

Study on Calculation Method for Pipe Crack Leakage

Wu Wanjun, Huang Xuan, Shen Pingchuan

2015, 36(S2): 122-126. doi: 10.13832/j.jnpe.2015.S2.0122

Abstract(42) PDF(0)

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The method to calculate the crack open displacement for circumference and axis through-wall cracks is introduced, and the method to predict the leakage based on Henry homogeneous and non-equilibrium flow model are presented. The method above is implemented by computer code, and comparison study between the test result from public literatures and calculate result is performed. The results show that the method can predict the crack open displacement and leakage effectively and be used for the LBB crack leak evaluation. It should be noted that the method is not a precise approach and some margin should be included in the application.

Application of ANSYS User Subroutine in Thermal Transient Analysis

XIe Hai, Gao Shiqing, ZHeng Liangang, Ceng Zhongxiu

2015, 36(S2): 127-130. doi: 10.13832/j.jnpe.2015.S2.0127

Abstract(34) PDF(1)

Abstract:
The thermal transient analysis result of the nuclear components contributes significant effect to the fatigue and fracture mechanics evaluation, and the key step of thermal analysis procedure is to apply the precise film coefficient. In this paper, the implement of applying the precise film coefficient is realized by using ANSYS user subroutine USERCV. The coding of USERCV subroutine, compiling and linking, application with example are also given in detail in this paper. Based on the comparison of the calculation, it is obvious that USERCV can reduce the conservative of fracture mechanic evaluation and fatigue analysis in a certain extent.

Effect of Interference Tolerance on Stress of Penetration of Reactor Pressure Vessel

Kuang Linyuan, Su Dongchuan, Wang Donghui, ZHeng Liangang, Shao Xuejiao

2015, 36(S2): 131-134. doi: 10.13832/j.jnpe.2015.S2.0131

Abstract(33) PDF(0)

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Based on the stress distribution in a hollow cylinder, the relation between the radial pressure and the interference tolerance is determined. Based on the maximum shear stress theory, theoretical expressions of the stress intensity of penetration and hole are given. For instance, the stress distribution of the penetration of the reactor pressure vessel is computed by theoretical expressions and finite element method. The computational results show that theoretical expressions of the penetration satisfy the requirement of engineering precision, and provide technical support for the design of the penetration of reactor pressure vessels.

Study on Analysis Methods of HCLPF of Pressurizer Support

Ye Xianhui, Cai Fengchun, Huang Qian, Shen Pingchuan, Zhang Yixiong

2015, 36(S2): 135-137. doi: 10.13832/j.jnpe.2015.S2.0135

Abstract(33) PDF(0)

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Calculation of the high confidence of low probability of failure（HCLPF） value of the structure, system and component（SSC） in nuclear power plants is an important process for seismic margin assessment（SMA）. In this paper, four methods for calculation of the HCLPF value of SSC are presented, such as, fragility analysis, conservative deterministic failure margin（CDFM）, HCLPF value based on testing, and the nonlinear time-history method. Subsequently based on the pressurizer model, the HCLPF of the supports of the pressurizer is obtained by nonlinear time history analysis and the CDFM method. The results show that two methods are different. The value of CDFM method is more conservative and the value of nonlinear time history method is more reasonable. It is suggested that the nonlinear time-history method is adopted to obtain the seismic capacity of nonlinear equipments.

Investigation of Calculation Method for Flow Characteristics and Flow Field between Tube Bundles

Huang Xuan, JIang Naibin, Qi Huanhuan

2015, 36(S2): 138-141. doi: 10.13832/j.jnpe.2015.S2.0138

Abstract(28) PDF(0)

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By using the computational fluid dynamic software FLUENT, on the basis of the mixture model, gas-liquid two phase flow around the cylinders with equivalent pitch is simulated to obtain the drag and lift forces on the central cylinder and the flow behavior of the whole calculating domain. The results show that the root mean square value and extreme value of the lift and drag forces on the central cylinder and the frequency of the vortex shedding increase with the growth of Reynolds number. The rationality is also validated with experimental results.

Study on Finite Simulation Technology for Seal Ring of Reactor Pressure Vessel

Shao Xuejiao, ZHeng Liangang, Su Dongchuan, Fu Xiaolong, Kuang Linyuan

2015, 36(S2): 142-145. doi: 10.13832/j.jnpe.2015.S2.0142

Abstract(28) PDF(0)

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Elasto-plastic analysis for the seal ring of reactor pressure vessel was done by nonlinear isotropic hardening constitutive model using ANSYS. The results of separating were obtained by three simulation means including uniform stress, spring elements and three-dimensional solid. The third way can reduce the excessive conservative part of the results effectively and improve the precision of sealing analysis.

Numerical Research on Hydrogen Mixing in an Experimental Device

Hou Liqiang, Tong Lili, Cao Xuewu, Peng Huanhuan

2015, 36(S2): 146-150. doi: 10.13832/j.jnpe.2015.S2.0146

Abstract(37) PDF(0)

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In this study, the CFX code is used to simulate the mixing phenomenon of hydrogen in the Large-Scale Gas Mixing Facility（LSGMF）. According to the experiment of hydrogen mixing conducted by AECL, a three-dimensional computational model of LSGMF is built and helium instead of hydrogen is injected into the facility. In order to adopt a suitable turbulence model, the standard k-ε, Shear Stress Transport and BSL Reynolds Stress turbulence model are discussed. Compared with the experiment data, it is found that the distribution of helium concentration when adopting the standard k-ε turbulence model is closest to the experiment results. In the end, through comparing the data of the helium distribution obtained by calculation with that obtained by experiment, it is found that the helium distribution is predicted well by the built computational model, which provides a good foundation for the further study of hydrogen mixing characteristics.

Improvement of RELAP5 Models Related to Reflood Phenomenon Based on Sensitivity Analysis

Li Dong, Xu Wei, Liu Xiaojing, Yang Yanhua

2015, 36(S2): 151-156. doi: 10.13832/j.jnpe.2015.S2.0151

Abstract(31) PDF(0)

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Reflood phenomenon is the third phase of large break loss of coolant accident（LBLOCA）, and it is also the most important stage to prevent it from developing towards severe accident. In order to improve the calculation accuracy of reflood with RELAP5 code, this paper performs sensitivity analysis against constitutive models of various flow regimes involved in the phenomenon. Then the model parameters which have a great influence on the results of interests including peak cladding temperature（PCT） and quench time are selected, and the improvement of these sensitive models are carried out with the help of recent advanced researches. FEBA（Flooding Experiment with Blocked Arrays） facility is used as the assessment experiment of this study. Through the contrast with six typical tests of FEBA experiment, an effective improvement of prediction accuracy is proved for the modified models.

Research and Application of STPA to Digital Reactor Shutdown System in NPP for System Safety Analysis

Liu Chaohui, Chen Zhi, Wu Zhiqiang, Liu Hua, Yang Xiaohua

2015, 36(S2): 157-161. doi: 10.13832/j.jnpe.2015.S2.0157

Abstract(36) PDF(2)

Abstract:
Most accidents are caused by dysfunctional interactions among components because of the widely used of digital technology and software nowadays. Traditional analysis methods cannot get a satisfactory result. In order to solve this problem, a new accident model named STAMP which based on system theoretic and STPA application methods. This paper introduces STPA method and its analysis steps in at first. Then we try to apply it for shutdown subsystem in NPPs and get the causal factors and safety constraints which should be obeyed in the design. It was useful for the design safety

2015 Vol. 36, No. S2